This project deals with the further characterization of chromosomal constituents in human nervous system tumors as compared to normal cells; for some purposes selected mouse neuroectodermal tumor models will also be used. We will attempt to find if there are specific DNA components that are amplified or decreased in the course of malignant transformation, or if DNA sequences are polyploid, that is represented in equal copy numbers as in the haploid genome. Other studies, directed at possible alterations in the localization and 3-dimensional position of such sequences with special reference to the interphase nucleus, will be simultaneously followed by light, transmission and scanning electron microscopy to elucidate if there is an abnormal location of these molecules in neoplastic cells. Progress in the last few years has indicated several repeated sequences, with specific and discrete chromosomal domains, are highly conserved in tumor cells (both in copy number and exact nucleotide sequence number), even in lines with up to hypohetaploid chromosome modes. A re-evaluation of the DNA content and polyploidy of tumor cells, selected by single cell cloning and cell sorting, and of nuclei from clinical specimens will be pursued. Restriction enzyme analysis combined with specific DNA probe hybridization will be measured on these isolates. Classes of DNA sequence in addition to repeated sequences, such as ribosomal cistrons or transcribed sequences, will be analyzed in order to determine if most sequences are represented evenly in cells with increased chromosome numbers. Intact nuclei from neuroectodermal tumors characterized here will serve as a substrate for the production of some potentially meaningful transcribed probes.